An image forming apparatus which prints an image such as a character and a figure on a recording medium such as a sheet using erasable coloring material is proposed. In addition, an apparatus having an image erasing function in the image forming apparatus like this is proposed.
An image forming apparatus having an image erasing function (hereinafter, simply called an image forming apparatus) forms an un-fixed toner image on a sheet with an electrographic system which uses erasable toner as erasable coloring material. When fixing the un-fixed toner image on the sheet (hereinafter, called a fixing mode), the image forming apparatus has a heating unit as a fixing unit which heats the un-fixed toner image to a prescribed fixing temperature and pressurizes the image. In the image forming apparatus, when the image printed on the sheet is erased (hereinafter, called an erasing mode), the heating unit functions also as an image erasing unit. The heating unit heats the toner image printed on the sheet at an erasing temperature higher than the fixing temperature, to erase the color of the toner image, or to make the color of the toner image transparent.
The heating unit keeps a heating temperature at the time of standby to the fixing temperature or a temperature close to the fixing temperature in the fixing mode, so as to perform a fixing operation without making a user wait. Accordingly, even if the erasing mode is selected by a user in the image forming apparatus, the image forming apparatus can not pass a sheet that is a target for image erasing to the heating unit until the heating temperature of the heating unit reaches from the fixing temperature to the erasing temperature.